Bump mocha from 8.4.0 to 9.0.0 in /samples/web-extension/javascript

Bumps [mocha](https://github.com/mochajs/mocha) from 8.4.0 to 9.0.0.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v8.4.0...v9.0.0)

---
updated-dependencies:
- dependency-name: mocha
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

samples/web-extension/javascript/package-lock.json

@@ -16,7 +16,7 @@
     "webextension-polyfill": "^0.8.0"
   },
   "devDependencies": {
-    "mocha": "^8.4.0",
+    "mocha": "^9.0.0",
     "typescript": "^4.3.2",
     "webpack": "^5.38.1",
     "webpack-cli": "^4.7.2"